chore: add pnp to gitignore (gatsbyjs#116)

Author: DSchau

.gitignore

@@ -1,8 +1,69 @@
-# Project dependencies
-.cache
-node_modules
-yarn-error.log
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (http://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
 
-# Build directory
-/public
+# Typescript v1 declaration files
+typings/
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# dotenv environment variables file
+.env
+
+# gatsby files
+.cache/
+public
+
+# Mac files
 .DS_Store
+
+# Yarn
+yarn-error.log
+.pnp/
+.pnp.js
+# Yarn Integrity file
+.yarn-integrity